A Lab reactor is a single-tube form of a parallel reactor. By designing different external jumper configurations for the reaction tubes, the tubes are connected in series within the reactor to achieve fixed modules, fixed lengths, and fixed scales for the Lab reactor unit. It is used for assembling rotary cutting flow test modules, rotary plug flow test modules, internal turbulence test modules, various pilot-scale skid-mounted systems, and other modules, skid-mounted units, and single-line reaction systems. It serves as an external unit for multi-line preheating, quenching units, matrix reactors, and single-line reactions, and can also function as an embedded component in some single-line reaction systems. It features high flexibility and strong external connectivity.